The present invention relates to a fast, monolithic integrated driver circuit for digital signals employing insulated-gate field-effect transistors which is connected between a load capacitance and the output of a stage capable of being loaded only with the comparatively small input capacitance of the driver circuit. To enable realizing the capacitance ratio of the load capacitance to the input capacitance, the driver circuit include inverters which are connected in series in relation to signal flow, with the switching transistors of the inverters having channel widths which, in direction of the signal flow, increase at least partially from stage to stage in accordance with a geometrical progression; such as that disclosed in German Pat. DE No. 1,487,398 B2.
Such types of MOS driver cirucits, of course, have the property of matching, depending on the number of stages, very large capacitance ratios with short switching times, but have the disadvantage that with an increasing number of stages, the total current flowing in the driver circuit is increased by the multiplication factor of the geometrical progression, because in such a series connection of inverters, in relation to signal flow, always approximately half of the inverters are traversed by current which, in the assumed case of a positive logic, corresponds to the lower binary level L at the output of these inverters. In cases where the series connection of inverters is realized by employing two inverters including enhancement transistors, such an arrangement is not sufficiently noise-proof with respect to certain cases of practical application, i.e. its signal-to-noise ratio is insufficient, with this being due to the fact that the signals corresponding to the high binary level H do not come close enough to the supply voltage.